Prognostic Significance of an 11-gene RNA Assay in Archival Tissue of Cutaneous Melanoma Stage I-III Patients

Purpose: The purpose of this study was to validate the results of an 11-gene expression profiling (GEP) assay which aims to improve the precision of individual prognosis beyond conventional American Joint Committee on Cancer staging for patients with cutaneous melanoma.

Methods: The reverse transcriptase polymerase chain reaction test of 11 prospectively selected genes was performed on 291 formalin-fixed, paraffin-embedded primary tumours of patients with stage I-III cutaneous melanoma. The expression levels of eight prognostic and three reference genes were used in a predefined algorithm to calculate a numerical score (-0.84 to 3.53) and then assign each patient to a preselected risk group (low versus high score) for melanoma-specific survival (MSS).

Results: One hundred twenty-seven patients were allocated to the low-score group, with a corresponding five-year disease-free survival (DFS) and MSS of 95% and 99%, respectively. 164 patients were allocated to the high-score group, with a corresponding five-year DFS and MSS of 78% and 88%. Continuous regression analysis demonstrated decreasing MSS probabilities with increasing scores. In a multivariate cox regression, only the 11-GEP, tumour thickness and age were statistically associated with MSS (p = 0.0068, 0.002 and 0.0159).

Conclusions: The 11-GEP has been validated as an independent predictor of outcome for melanoma patients. More specifically, using an 11-GEP score cut-off of ≤0, the assay can identify patient cohorts with 10-year survival probabilities well above 90%. This information may be used in the decision-making for a potential adjuvant therapy.